This invention relates to a combination valve and manifold assembly for a compressed air storage tank or the like.
Generally, it is desirable that a compressed air storage tank have as few openings as possible therein. However, it is often necessary to provide ports for a pressure gauge and for a safety relief valve as well as a main air outlet. Heretofore, manifold assemblies were known which provided a main air outlet, a shutoff valve for the outlet, and other outlet ports for connection of a pressure gauge, a pressure relief valve, or the like. In one of these prior art manifold assemblies, such as shown in U.S. Pat. No. 3,231,236, a slide valve is used to block the flow from the main outlet. This slide valve is, however, subject to wear and leakage and it severely restricts flow through the main outlet.
In the manifold assembly of the present invention, a ball valve is used as the flow shutoff valve. The advantages of ball valves (i.e., low pressure drop and high flow through the valve, and the fast opening and closing action of the valve) are well known. However, known ball valves, when subjected to fluid pressure often bind in their valve seats. It is also necessary that the ball valve member be sealingly mated with its valve seat. In some ball valves, unequal pressure forces exerted on opposite sides of the ball valve member caused it to bind on its valve seat and to unevenly contact its seat thus resulting in leakage, and made the valve difficult to operate. In some instances, these unbalanced pressure forces caused damage to the valve. Also, the seals and the construction of many ball valve designs are complicated.